Sporadic and Familial Hemiplegic Migraine - The Basics

To understand Hemiplegic Migraine, we have to understand that Migraine attacks are episodic manifestations of a genetic neurological disease. Migraine can present in a variety of ways. Hemiplegic Migraine is a rare form of Migraine, made more confusing by there being two variations: Familial Hemiplegic Migraine (FHM) and Sporadic Hemiplegic Migraine (SHM).

Both FHM and SHM often begin in childhood and cease during adult years. Diagnosing FHM and SHM can be difficult as the symptoms are also indicative of vascular disease and can be thought to be stroke, epilepsy, or other conditions. A full neurological work up and careful review of medical history and symptoms are necessary to rule out other causes and confirm a diagnosis of FHM or SHM. Family medical history is especially helpful in diagnosing FHM.

FHM and SHM share symptoms, which will vary among different Migraineurs. The difference between the two is that FHM can be traced back in the family history and has been linked to mutations of specific genes, which are discussed more fully below. SHM is FHM without the familial connection and that particular genetic mutation.

Treatment of FHM and SHM:

Treatment of Hemiplegic Migraine can be challenging. The symptoms are greater in number and more difficult to treat. Those who experience Hemiplegic Migraines absolutely need to educate themselves about their disease and treatment. It’s very common to need to seek the care of an excellent Migraine specialist with an established track record for treatment as many other doctors have never treated a case of Hemiplegic Migraine.

Abortive and Pain Relief**: Migraine-specific abortives, the triptans and ergotamines, are currently contraindicated in the treatment of Hemiplegic Migraine because of their vasoconstrictive properties and concerns about stroke. One small study was conducted, safely using triptans with patients with Hemiplegic Migraine, but more trials are needed before they’re considered a safe option.2 More recently, a poster presentation at the 2014 annual scientific meeting of the American Headache Society questioned this contraindication. You can find the details in Triptans for Hemiplegic and Basilar Migraine? New Study. When doctors feel the triptans and ergotamines aren’t options, other treatments such as NSAID’s, antiemetics, and narcotic analgesics are generally used for symptomatic relief of Hemiplegic Migraine.

Preventive: Given the severity of the symptoms and the contraindication of abortive medications, preventive regimens are considered especially important in the treatment of Hemiplegic Migraine. The genes for FHM are mapped on chromosomes 1 and 19, These code for the calcium channel. "The mutant calcium channel does not open and close properly and cannot regulate the amount of calcium coming into the cell, so calcium influx and efflux regulation goes awry. This in turn leads to neurons firing too easily."3 For this reason, calcium channel blockers are sometimes especially effective preventive medications for FHM.

A Word of Caution:

Migraineurs with Hemiplegic Migraine should give special consideration to wearing some kind of medical identification at all times since an attack can lead to impaired consciousness and an inability to speak. Medical identification can save valuable time in an emergency and assure that proper treatment is received far more quickly.

More on Symptoms and Diagnosis:

In the field of “headache medicine,” the gold standard for diagnosing and classifying migraine and other headache disorders is the International Headache Society’s International Classification of Headache Disorders, 3rd edition (ICHD-3). Here is the most recent information on hemiplegic migraine from ICHD-3:

1.2.3 Hemiplegic migraine

Description: Migraine with aura including motor weakness.

Diagnostic criteria:

At least two attacks fulfilling criteria B and C

Aura consisting of both of the following:

fully reversible motor weakness

fully reversible visual, sensory and/or speech/language symptoms

At least two of the following four characteristics:

at least one aura symptom spreads gradually over 5 minutes or more, and/or two or more symptoms occur in succession

each individual non-motor aura symptom lasts 5-60 minutes, and motor symptoms last less than 72 hours2

at least one aura symptom is unilateral3

the aura is accompanied, or followed within 60 minutes, by headache

Not better accounted for by another ICHD-3 diagnosis, and transient ischaemic attack and stroke have been excluded.

Notes:

The term plegic means paralysis in most languages, but most attacks are characterized by motor weakness.

In some patients, motor weakness may last weeks.

Aphasia is always regarded as a unilateral symptom; dysarthria may or may not be.

Comment: It may be difficult to distinguish weakness from sensory loss.

1.2.3.1 Familial hemiplegic migraine (FHM)

Description: Migraine with aura including motor weakness and at least one first- or second-degree relative has migraine aura including motor weakness.

Diagnostic criteria:

Fulfils criteria for 1.2.3 Hemiplegic Migraine

At least one first- or second-degree relative has had attacks fulfilling criteria for 1.2.3 Hemiplegic migraine.

Comments:

New genetic data have allowed a more precise definition of 1.2.3.1 Familial hemiplegic migraine (FHM) than was possible previously. Specific genetic subtypes have been identified: in FHM1 there are mutations in the CACNA1A gene (coding for a calcium channel) on chromosome 19; in FHM2 there are mutations in the ATP1A2 gene (coding for a K/Na-ATPase) on chromosome 1; and in FHM3 there are mutations in the SCN1A gene (coding for a sodium channel) on chromosome 2. There may be other loci not yet identified. When genetic testing is done, the genetic subtype (if discovered) should be specified at the fifth digit.

It has been shown that 1.2.3.1 Familial hemiplegic migraine (FHM) very often presents with brainstem symptoms in addition to the typical aura symptoms, and that headache almost always occurs. Rarely, during FHM attacks, disturbances of consciousness (sometimes including coma), confusion, fever and CSF pleocytosis can occur.

1.2.3.1 Familial hemiplegic migraine (FHM) may be mistaken for epilepsy and (unsuccessfully) treated as such. FHM attacks can be triggered by (mild) head trauma. In approximately 50% of FHM families, chronic progressive cerebellar ataxia occurs independently of the migraine attacks.

Subtypes of Familial Hemiplegic Migraine:

When genetic testing is available and has been performed, the results of that testing may be used to diagnose more specifically hemiplegic migraine falling into these subtypes:

Epidemiological studies have shown that sporadic cases occur with approximately the same prevalence as familial cases.

The attacks in 1.2.3.2 Sporadic hemiplegic migraine have the same clinical characteristics as those in 1.2.3.1 Familial hemiplegic migraine. Some apparently sporadic cases have known FHM mutations, and in some a first or second-degree relative later develops hemiplegic migraine, thus completing fulfillment of the criteria for 1.2.3.1 Familial hemiplegic migraine and requiring a change of diagnosis.

Sporadic cases usually require neuroimaging and other tests to rule out other causes. A lumbar puncture may be necessary to rule out 7.3.5 Syndrome of transient Headache and Neurological Deficits with cerebrospinal fluid Lymphocytosis (HaNDL).

Summary and Comments:

Although it’s still said that hemiplegic migraine is a rare form of migraine, some experts theorize that it may not be as rare as has been thought; that hemiplegic migraine is perceived as rare because it’s poorly understood and not diagnosed. Because many of its symptoms are also symptoms of other issues such as stroke and epilepsy, hemiplegic migraine attack can be quite frightening, both to the migraineur and to those witnessing the attacks.

Proper diagnosis and treatment are especially essential with this form of migraine. Imaging studies and other testing should be performed to rule out other causes of the symptoms. It’s important that people with hemiplegic migraine understand their migraines as well as possible and not panic when they occur. With continuing research, especially genetic research, more is being learned about hemiplegic migraine. As this research continues, living with hemiplegic migraine will become easier.